1. Field of the Invention
This disclosure relates to the field of expandable luggage, in particular to expandable luggage utilizing an expansion mechanism to help support the luggage in the expanded state.
2. Description of the Related Art
The needs of travelers for transport space in their luggage can vary considerably. Some factors to consider are the duration of a trip, the type of trip (whether business or pleasure), the destination of the trip, and the activities to be performed during the trip. For instance, a user on a short trip will generally require less space for packing than a user on a long trip. By the same token, a user on a business trip often requires less clothing than on a pleasure trip where both dress and casual clothes may be needed. A traveler to a warm climate will also generally require less storage space than one going to a cold climate as warm weather clothes are generally less bulky.
Because of aircraft and airport luggage restrictions for both carry-on and checked baggage, travelers generally do not want to carry suitcases that are the incorrect size for their needs as the last thing a traveler wants to do is be forced to check a half empty piece of luggage, or be forced to deal with a large number of small pieces of luggage as they can be difficult to carry and keep track of and may not be allowed on the airplane.
To deal with these problems, many travelers own a multiplicity of luggage of various different sizes, shapes, and/or styles. They can then select the appropriate luggage for the particular type of trip they are currently taking so as to have a luggage that is not too large or too small. The problem with this situation is that it requires the luggage owner to own a number of pieces of luggage to be able to have the selection to chose from. Many pieces of luggage, even so-called soft-sided luggage (which generally include a rigid frame), are not collapsible and therefore storage of the selection of luggage can take up quite a lot of space. Further, even if the user selects the correct piece of luggage for the original trip, they may make purchases or otherwise acquire items at their destination requiring a larger piece of luggage for their return trip than was required for their initial trip.
To try and combat this problem, various types of expandable luggage have been developed. The simplest of these is a duffel bag, bag, or purse which is simply manufactured of a flexible material without any rigid structure. These can then be compressed into another suitcase for travel and unfolded and used for transport if additional space is later needed. The problem with these, however, is that they provide no shape to the luggage which can result in damage to the luggage or contents depending on what is carried and may not be suitable for some types of use. Further, many of these bags do not seal and so may not be used as checked luggage.
Another proposed solution to the problem has been the design of various expansible luggage or luggage of variable volume. This luggage generally has two portions or frames which are moveable relative to each other so that in a first configuration the luggage has a predetermined first volume, and in the second configuration a predetermined second volume which is greater than the first. These types of luggage can have all sorts of different designs. Some designs utilize zipped flaps which when unzipped allow a piece of flexible material to be extended between the two frames, the material then forming a portion of the outer wall of the luggage allowing for a larger internal volume.
While this design has its advantages, a distinct disadvantage is that there is no support for the flexible section. Therefore, the frames will often not naturally sit in the expanded position. This can make packing difficult. In particular, because of the design of the frames of soft sided or hard-sided luggage, the two frames are generally above each other with the flexible section between them when the luggage is being loaded. The weight of the top frame will generally collapse the flexible section meaning that the bag is often loaded to a guessed volume, and then the upper frame is lifted by the user to determine if the fill is correct.
To try and make expansible bags easier to load, a variety of expansion mechanisms or “expanders” have been proposed. These are devices which serve to provide a rigid or semi rigid support to the upper frame holding the frames apart to retain their spaced position. In this way, the flexible section is not collapsed as the two frames are held or supported at a particular distance from each other by the expansion mechanism. As the expansion mechanism serves to hold the bag in the expanded position, it improves ease of packing by holding the bag at the larger internal volume while the bag is being packed.
There are a plethora of problems with existing designs for expansion mechanisms. In many of the designs, the expansion mechanism maintains the positioning through a rigid locking of the expander in one or more positions which expand the volume of the luggage. The user moves the expander to a desired position for a particular expansion, and then locks it rigidly into place. To move the two frame pieces relative to each other to collapse the luggage, the user releases the lock, moves the expander, and then reengages the lock. These locks range from pins, to ratcheting mechanisms, to rotating cam locks. For weight reasons, these expanders are regularly constructed of lightweight plastic components and fabrics.
While these systems promote ease of use when loading the bag, they can present problems when the bag is in use. In particular, when a bag is expanded, it may or may not be fully loaded, or may be loaded with compressible items. In either case, baggage is often treated quite roughly by baggage handlers in loading or unloading the aircraft, and in transferring baggage from the airline to the user. It is, therefore, not surprising for a large force to be applied to the baggage. Because of these system's rigid locking mechanisms holding them in the expanded state, such a force can quite easily break the locking mechanism by snapping pins, teeth, or similar components which serve to lock the expansion mechanism in the extended position. This can destroy the functionality of the expansion device rendering it completely unusable and resulting in a costly repair.
In still other systems, the expander may comprise a plate rigidly held between rails or within a socket. These systems provide for increased rigidity to prevent the frames from moving relative to each other, and provide for a more rigidly sliding structure. Even if a force on the luggage is not from the correct angle to damage the locking mechanism, such as if a shearing force is applied, the plates or rails may be bent or even broken by the force. Because these systems rely on precise distances, designs, and relationships for smooth extension by sliding portions, a bend or break can easily prevent the expansion mechanism from operating as the bend or break results in a bind in the system, locking it to a particular position or subset of desired positions as the parts can no longer slide. In some cases, the force could be hard enough to break the plate, break the rails, or separate the plate from the rails. The problem is akin to a rail car wherein, if the wheel or tracks are damaged or bent, the train can easily derail.
A still further problem with the systems of the prior art is that they allow moving components of the expansion mechanisms to interact with the contents of the luggage. In particular, clothing or other items already placed in the luggage can be caught in moving parts of the expansion mechanism which extend into an already packed volume. This can both damage the mechanism and can result in damage to the items placed in the luggage. There can also be dirt or lint buildup in the system resulting in additional chances for binding